'use strict';

var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };

var isMergeableObject = function () {
	return function isMergeableObject(value) {
		return isNonNullObject(value) && !isSpecial(value);
	};

	function isNonNullObject(value) {
		return !!value && (typeof value === 'undefined' ? 'undefined' : _typeof(value)) === 'object';
	}

	function isSpecial(value) {
		var stringValue = Object.prototype.toString.call(value);

		return stringValue === '[object RegExp]' || stringValue === '[object Date]' || isReactElement(value);
	}

	var canUseSymbol = false;
	var REACT_ELEMENT_TYPE = 0xeac7;
	try {
		// canUseSymbol = typeof Symbol === 'function' && Symbol.for
		// if (canUseSymbol) {
		//     REACT_ELEMENT_TYPE = canUseSymbol ? Symbol.for('react.element') : 0xeac7;
		// }
	} catch (e) {}

	function isReactElement(value) {
		return value.$$typeof === REACT_ELEMENT_TYPE;
	}
}();

function emptyTarget(val) {
	return Array.isArray(val) ? [] : {};
}

function cloneUnlessOtherwiseSpecified(value, optionsArgument) {
	var clone = !optionsArgument || optionsArgument.clone !== false;

	return clone && isMergeableObject(value) ? deepmerge(emptyTarget(value), value, optionsArgument) : value;
}

function defaultArrayMerge(target, source, optionsArgument) {
	return target.concat(source).map(function (element) {
		return cloneUnlessOtherwiseSpecified(element, optionsArgument);
	});
}

function mergeObject(target, source, optionsArgument) {
	var destination = {};
	if (isMergeableObject(target)) {
		Object.keys(target).forEach(function (key) {
			destination[key] = cloneUnlessOtherwiseSpecified(target[key], optionsArgument);
		});
	}
	Object.keys(source).forEach(function (key) {
		if (!isMergeableObject(source[key]) || !target[key]) {
			destination[key] = cloneUnlessOtherwiseSpecified(source[key], optionsArgument);
		} else {
			destination[key] = deepmerge(target[key], source[key], optionsArgument);
		}
	});
	return destination;
}

function deepmerge(target, source, optionsArgument) {
	var sourceIsArray = Array.isArray(source);
	var targetIsArray = Array.isArray(target);
	var options = optionsArgument || { arrayMerge: defaultArrayMerge };
	var sourceAndTargetTypesMatch = sourceIsArray === targetIsArray;

	if (!sourceAndTargetTypesMatch) {
		return cloneUnlessOtherwiseSpecified(source, optionsArgument);
	} else if (sourceIsArray) {
		var arrayMerge = options.arrayMerge || defaultArrayMerge;
		return arrayMerge(target, source, optionsArgument);
	} else {
		return mergeObject(target, source, optionsArgument);
	}
}

deepmerge.all = function deepmergeAll(array, optionsArgument) {
	if (!Array.isArray(array)) {
		throw new Error('first argument should be an array');
	}

	return array.reduce(function (prev, next) {
		return deepmerge(prev, next, optionsArgument);
	}, {});
};

module.exports = deepmerge;